To study behavioral effects and recovery following somatosensory with accompanying motor deprivation during early months (0 to 6 mos.) of development in stumptail macaque monkeys, 12 male infants will be reared under 3 conditions: isolation for 3 months, isolation for 3 months followed by social rearing for 3 months, social rearing for 3 months. Results will be compared with known effects of isolation vs. social rearing for 6 months. The development of sensory projection areas and motor areas of the cerebral cortex will be studied by Golgi-Cox and rapid Golgi techniques for determining dendrite branching and spine development. The cerebellum will be investigated for relative stages of cell migration from external to internal granular layers and for the development of cell processes and cell soma in cells of all 3 layers of the cerebellum. Brain samples will also be tested for uptake and for receptor binding of transmitters such as GABA and Norepinephrine, and for DNA per unit volume. Daily behavioral observations will provide data on such items as self clutching, self biting, bizarre body orientation, hopping in place, and gross body jerks. At 3 months and at 6 months, tests of motor coordination, fear of being jostled or other passive movements, and avoidance of unfamiliar animate and inanimate stimuli will be evaluated.